[Veritas-bu] DLT8000's in a SAN: par performance?
2002-04-12 15:52:09
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my wording was wrong. I'm not using any software compression in any class
just the hardware compression on the tape drive. According to Mark
Donaldson
NBU reports the actual data sent to the tape drive. What gets me is the
number reported is a little less than half the space occupied by the mount
points
I chose for this paritcular backup. This contradicts the possibility that
NBU
reported the amount of 'compressed' data put on tape....
-----Original Message-----
From: Larry Kingery [mailto:larry.kingery AT veritas DOT com]
Sent: Friday, April 12, 2002 3:25 PM
To: Markham, Richard
Subject: Re: [Veritas-bu] DLT8000's in a SAN: par performance?
4.5 MB/s is probably the disk speed. It's also possible that you're
losing some by "compressing" compressed data.
If the data is already compressed by some reasonable means, you can
forget all about 80GB/tape, you'll probably get more like 37.
You'll also probably need a larger SIZE_DATA_BUFFERS to get much more
than that out of a Sun.
Markham, Richard writes:
> I wrote 30gb of compressed data to tape over fiber at
> 4.5mb/s. These are QUANTUM DLT8000 tape drives and
> they claim they are able to run 40gb @ 6mb per second
> and 80gb compressed @ 12gb/s given that since I was
> running over a dedicated san from a E420R I thought
> perhaps I should be in the 7-8mb/s range. Thanks for
> any input.
>
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> <P><FONT SIZE=2>I wrote 30gb of compressed data to tape over fiber
at</FONT>
> <BR><FONT SIZE=2>4.5mb/s. These are QUANTUM DLT8000 tape drives and
</FONT>
> <BR><FONT SIZE=2>they claim they are able to run 40gb @ 6mb per
second</FONT>
> <BR><FONT SIZE=2>and 80gb compressed @ 12gb/s given that since I was
</FONT>
> <BR><FONT SIZE=2>running over a dedicated san from a E420R I thought
</FONT>
> <BR><FONT SIZE=2>perhaps I should be in the 7-8mb/s range. Thanks
for </FONT>
> <BR><FONT SIZE=2>any input.</FONT>
> </P>
>
> </BODY>
> </HTML>
--
Larry Kingery
I don't believe anything that can be stated in a single sentence.
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<P><FONT SIZE=2>my wording was wrong. I'm not using any software
compression in any class</FONT>
<BR><FONT SIZE=2>just the hardware compression on the tape drive.
According to Mark Donaldson</FONT>
<BR><FONT SIZE=2>NBU reports the actual data sent to the tape drive. What
gets me is the </FONT>
<BR><FONT SIZE=2>number reported is a little less than half the space occupied
by the mount points</FONT>
<BR><FONT SIZE=2>I chose for this paritcular backup. This contradicts the
possibility that NBU</FONT>
<BR><FONT SIZE=2>reported the amount of 'compressed' data put on tape....</FONT>
</P>
<BR>
<P><FONT SIZE=2>-----Original Message-----</FONT>
<BR><FONT SIZE=2>From: Larry Kingery [<A HREF="mailto:larry.kingery AT veritas
DOT com">mailto:larry.kingery AT veritas DOT com</A>]</FONT>
<BR><FONT SIZE=2>Sent: Friday, April 12, 2002 3:25 PM</FONT>
<BR><FONT SIZE=2>To: Markham, Richard</FONT>
<BR><FONT SIZE=2>Subject: Re: [Veritas-bu] DLT8000's in a SAN: par
performance?</FONT>
</P>
<BR>
<P><FONT SIZE=2>4.5 MB/s is probably the disk speed. It's also possible
that you're</FONT>
<BR><FONT SIZE=2> losing some by "compressing" compressed
data.</FONT>
</P>
<P><FONT SIZE=2>If the data is already compressed by some reasonable means, you
can</FONT>
<BR><FONT SIZE=2>forget all about 80GB/tape, you'll probably get more like
37.</FONT>
</P>
<P><FONT SIZE=2>You'll also probably need a larger SIZE_DATA_BUFFERS to get
much more</FONT>
<BR><FONT SIZE=2>than that out of a Sun.</FONT>
</P>
<P><FONT SIZE=2>Markham, Richard writes:</FONT>
<BR><FONT SIZE=2>> I wrote 30gb of compressed data to tape over fiber at
</FONT>
<BR><FONT SIZE=2>> 4.5mb/s. These are QUANTUM DLT8000 tape drives and
</FONT>
<BR><FONT SIZE=2>> they claim they are able to run 40gb @ 6mb per second
</FONT>
<BR><FONT SIZE=2>> and 80gb compressed @ 12gb/s given that since I was
</FONT>
<BR><FONT SIZE=2>> running over a dedicated san from a E420R I thought
</FONT>
<BR><FONT SIZE=2>> perhaps I should be in the 7-8mb/s range. Thanks
for </FONT>
<BR><FONT SIZE=2>> any input. </FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML
3.2//EN"></FONT>
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Exchange Server version 5.5.2650.12"></FONT>
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performance?</TITLE></FONT>
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<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> <P><FONT SIZE=2>I wrote 30gb of compressed
data to tape over fiber at</FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>4.5mb/s.&nbsp; These are
QUANTUM DLT8000 tape drives and </FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>they claim they are able to
run 40gb @ 6mb per second</FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>and 80gb compressed @ 12gb/s
given that since I was </FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>running over a dedicated san
from a E420R I thought </FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>perhaps I should be in the
7-8mb/s range.&nbsp; Thanks for </FONT></FONT>
<BR><FONT SIZE=2>> <BR><FONT SIZE=2>any
input.</FONT></FONT>
<BR><FONT SIZE=2>> </P></FONT>
<BR><FONT SIZE=2>> </FONT>
<BR><FONT SIZE=2>> </BODY></FONT>
<BR><FONT SIZE=2>> </HTML></FONT>
<BR><FONT SIZE=2>-- </FONT>
<BR><FONT SIZE=2>Larry Kingery </FONT>
<BR><FONT SIZE=2> I don't believe anything that can be stated in a single
sentence.</FONT>
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